linux-kernel - [PATCH 1/5] s390/mm: make hugepages

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-Id: <1432813957-46874-2-git-send-email-dingel@linux.vnet.ibm.com>
Date:	Thu, 28 May 2015 13:52:33 +0200
From:	Dominik Dingel <dingel@...ux.vnet.ibm.com>
To:	linux-kernel@...r.kernel.org
Cc:	Russell King <linux@....linux.org.uk>,
	Catalin Marinas <catalin.marinas@....com>,
	Will Deacon <will.deacon@....com>,
	Tony Luck <tony.luck@...el.com>,
	Fenghua Yu <fenghua.yu@...el.com>,
	James Hogan <james.hogan@...tec.com>,
	Ralf Baechle <ralf@...ux-mips.org>,
	Benjamin Herrenschmidt <benh@...nel.crashing.org>,
	Paul Mackerras <paulus@...ba.org>,
	Michael Ellerman <mpe@...erman.id.au>,
	Martin Schwidefsky <schwidefsky@...ibm.com>,
	Heiko Carstens <heiko.carstens@...ibm.com>,
	linux390@...ibm.com, "David S. Miller" <davem@...emloft.net>,
	Chris Metcalf <cmetcalf@...hip.com>,
	Thomas Gleixner <tglx@...utronix.de>,
	Ingo Molnar <mingo@...hat.com>,
	"H. Peter Anvin" <hpa@...or.com>, x86@...nel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Zhang Zhen <zhenzhang.zhang@...wei.com>,
	Dominik Dingel <dingel@...ux.vnet.ibm.com>,
	David Rientjes <rientjes@...gle.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	Nathan Lynch <nathan_lynch@...tor.com>,
	Christian Borntraeger <borntraeger@...ibm.com>,
	Andy Lutomirski <luto@...capital.net>,
	Michael Holzheu <holzheu@...ux.vnet.ibm.com>,
	Hugh Dickins <hughd@...gle.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Paolo Bonzini <pbonzini@...hat.com>,
	"Jason J. Herne" <jjherne@...ux.vnet.ibm.com>,
	Davidlohr Bueso <dave@...olabs.net>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Luiz Capitulino <lcapitulino@...hat.com>,
	Mike Kravetz <mike.kravetz@...cle.com>,
	linux-arm-kernel@...ts.infradead.org, linux-ia64@...r.kernel.org,
	linux-metag@...r.kernel.org, linux-mips@...ux-mips.org,
	linuxppc-dev@...ts.ozlabs.org, linux-s390@...r.kernel.org,
	linux-sh@...r.kernel.org, sparclinux@...r.kernel.org,
	linux-mm@...ck.org
Subject: [PATCH 1/5] s390/mm: make hugepages_supported a boot time decision

By dropping support for hugepages on machines which do not have
the hardware feature EDAT1, we fix a potential s390 KVM bug.

The bug would happen if a guest is backed by hugetlbfs (not supported currently),
but does not get pagetables with PGSTE.
This would lead to random memory overwrites.

Acked-by: Martin Schwidefsky <schwidefsky@...ibm.com>
Signed-off-by: Dominik Dingel <dingel@...ux.vnet.ibm.com>
---
 arch/s390/include/asm/page.h | 8 ++++----
 arch/s390/kernel/setup.c     | 2 ++
 arch/s390/mm/pgtable.c       | 2 ++
 3 files changed, 8 insertions(+), 4 deletions(-)

diff --git a/arch/s390/include/asm/page.h b/arch/s390/include/asm/page.h
index 53eacbd..0844b78 100644
--- a/arch/s390/include/asm/page.h
+++ b/arch/s390/include/asm/page.h
@@ -17,7 +17,10 @@
 #define PAGE_DEFAULT_ACC	0
 #define PAGE_DEFAULT_KEY	(PAGE_DEFAULT_ACC << 4)
 
-#define HPAGE_SHIFT	20
+#include <asm/setup.h>
+#ifndef __ASSEMBLY__
+
+extern unsigned int HPAGE_SHIFT;
 #define HPAGE_SIZE	(1UL << HPAGE_SHIFT)
 #define HPAGE_MASK	(~(HPAGE_SIZE - 1))
 #define HUGETLB_PAGE_ORDER	(HPAGE_SHIFT - PAGE_SHIFT)
@@ -27,9 +30,6 @@
 #define ARCH_HAS_PREPARE_HUGEPAGE
 #define ARCH_HAS_HUGEPAGE_CLEAR_FLUSH
 
-#include <asm/setup.h>
-#ifndef __ASSEMBLY__
-
 static inline void storage_key_init_range(unsigned long start, unsigned long end)
 {
 #if PAGE_DEFAULT_KEY
diff --git a/arch/s390/kernel/setup.c b/arch/s390/kernel/setup.c
index a5ea8bc..9ac282b 100644
--- a/arch/s390/kernel/setup.c
+++ b/arch/s390/kernel/setup.c
@@ -915,6 +915,8 @@ void __init setup_arch(char **cmdline_p)
 	 */
 	setup_hwcaps();
 
+	HPAGE_SHIFT = MACHINE_HAS_HPAGE ? 20 : 0;
+
 	/*
 	 * Create kernel page tables and switch to virtual addressing.
 	 */
diff --git a/arch/s390/mm/pgtable.c b/arch/s390/mm/pgtable.c
index b2c1542..f76791e 100644
--- a/arch/s390/mm/pgtable.c
+++ b/arch/s390/mm/pgtable.c
@@ -36,6 +36,8 @@
 #endif
 
 
+unsigned int HPAGE_SHIFT;
+
 unsigned long *crst_table_alloc(struct mm_struct *mm)
 {
 	struct page *page = alloc_pages(GFP_KERNEL, ALLOC_ORDER);
-- 
2.3.7

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/